SEARCH · PubMed Health

Results for “Hydroxybutyrates”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7Linked to original sources

PubMed1997

Biosynthesis of poly(4-hydroxybutyric acid) by recombinant strains of Escherichia coli.

The aim of this study was the production of the homopolyester poly(4-hydroxybutyric acid) (poly(4HB)) with recombinant strains of Escherichia coli. Wild-type strains and other widely used non-recombinant strains of E. coli are not able to produce polyhydroxyalkanoic acids (PHA) as storage compounds and cannot utilize 4-hydroxybutyric acid as sole carbon source. Accordingly, hybrid plasmids of pBluescript vectors were constructed which harbored the Alcaligenes eutrophus PHA synthase gene (phaC) and the Clostridium kluyveri orfZ putatively encoding a 4-hydroxybutyric acid-coenzyme A transferase. A 3.5-kb genomic SmaI/ApaI fragment from A. eutrophus, which comprises phaC, and a 1.8-kb genomic ApaI/EcoRI fragment from C kluyveri, which contained orfZ, were inserted into the SmaI and EcoRI sites of the vectors pKS- and pSK-, respectively. The two resulting plasmids pSKSE5.3 and pKSSE5.3 comprising phaC and orfZ colinear or antilinear to lacZ, respectively, were transformed into E. coli XL1-Blue. Recombinant strains synthesized the homopolyester poly(4HB), when the cells were cultivated in Luria-Bertani broth and if glucose and 4-hydroxybutyric acid were provided as carbon sources. If glucose was omitted, a copolyester of 3-hydroxybutyric acid and 4-hydroxybutyric acid was accumulated. The homopolyester poly(4HB) was also accumulated during cultivation of these strains in M9 mineral salts medium containing glucose plus 4-hydroxybutyric acid as carbon sources. Poly(4HB) could amount up to approximately 80% (w/w) of the cell dry matter if E. coli XL1-Blue harboring pKSSE5.3 was cultivated in M9 mineral salts medium and if the cultures were not sufficiently supplied with oxygen. 4HB was also incorporated into PHA if gamma-butyrolactone was used as carbon source. If levulinic acid, 4-hydroxyvaleric acid or gamma-valerolactone were used as carbon sources, only very low amounts of PHA were accumulated which did not contain 4-hydroxyalkanoic acids as constituents.

4-Butyrolactone↗

PubMed2005

Novel intracellular 3-hydroxybutyrate-oligomer hydrolase in Wautersia eutropha H16.

Wautersia eutropha H16 (formerly Ralstonia eutropha) mobilizes intracellularly accumulated poly(3-hydroxybutyrate) (PHB) with intracellular poly(3-hydroxybutyrate) depolymerases. In this study, a novel intracellular 3-hydroxybutyrate-oligomer hydrolase (PhaZc) gene was cloned and overexpressed in Escherichia coli. Then PhaZc was purified and characterized. Immunoblot analysis with polyclonal antiserum against PhaZc revealed that most PhaZc is present in the cytosolic fraction and a small amount is present in the poly(3-hydroxybutyrate) inclusion bodies of W. eutropha. PhaZc degraded various 3-hydroxybutyrate oligomers at a high specific activity and artificial amorphous poly(3-hydroxybutyrate) at a lower specific activity. Native PHB granules and semicrystalline PHB were not degraded by PhaZc. A PhaZ deletion mutation enhanced the deposition of PHB in the logarithmic phase in nutrient-rich medium. PhaZc differs from the hydrolases of W. eutropha previously reported and is a novel type of intracellular 3-hydroxybutyrate-oligomer hydrolase, and it participates in the mobilization of PHB along with other hydrolases.

Amino Acid Sequence↗

PubMed2025

Epigenetic Histone β-Hydroxybutyrylation Contributes to Renoprotection by β-Hydroxybutyrate in the Dahl Rat.

BACKGROUND: Previously, we demonstrated that the ketone body, β-hydroxybutyrate, is a potent antihypertensive and reno-protective metabolite in Dahl Salt-Sensitive rats. However, the mechanism by which β-hydroxybutyrate confers these beneficial effects is understudied. Here we focused on determining whether the reno-protective effect of β-hydroxybutyrate is due to its known ability to epigenetically remodel chromatin via histone β-hydroxybutyrylation. METHODS: We used the same animal protocol previously used for the discovery of the reno-protective effect of β-hydroxybutyrate. Briefly, postweaning, male and female Dahl Salt-Sensitive rats were split into 2 groups and supplemented with or without 1,3-butanediol for 6 weeks. At euthanasia, circulating β-hydroxybutyrate was quantitated. Renal homogenates were examined for histone 3 lysine 9 β-hydroxybutyrylation, chromatin occupancy, transcriptomic and proteomic profiles with validations. RESULTS: Rats supplemented with 1,3-butanediol had higher circulating β-hydroxybutyrate, renal histone β-hydroxybutyrylation, and significant remodeling of chromatin. Notably, regions of the genome associated with lipid catabolism were predominantly in an open chromatin configuration, leading to active transcription and translation. The most highly upregulated gene actively transcribed and translated was Hmgcs2 (3-hydroxy-3-methylglutaryl CoA synthase 2), a gene responsible for the biosynthesis of β-hydroxybutyrate in mitochondria. In contrast, regions with more compact chromatin structures contained immune function genes, Ptprc (protein tyrosine phosphatase receptor type C) and Lcp1 (lymphocyte cytosolic protein 1), which were suppressed. CONCLUSIONS: These results reveal that renal epigenetic histone β-hydroxybutyrylation is a novel mechanism by which transcriptional regulation of both energy metabolism and immune function occur concomitantly and contribute to renoprotection in the hypertensive Dahl rat.

Animals↗

PubMedDate not supplied

Chirality of the Hydrogen transfer to NAD catalyzed by (3R) hydroxybutyrate dehydrogenase from Pseudomonas lemoignei.

The chirality of the hydrogen transfer from (3R) hydroxybutyrate to NAD catalyzed by (3R)hydroxybutyrate dehydrogenase (E.C. 1.1.1.30, D-3-hydroxybutyrate : NAD oxidoreductase) from Pseudomonas lemoignei was investigated. [4(-3)H] NAD was enzymatically reduced to (4R) [4(-3)H]NADH with (3RS) hydroxybutyrate. This observation was confirmed since NAD could be reduced to (4S) [4(-3)H] NADH with (3RS) [3(-3)H] hydroxybutyrate and (3R) hydroxybutyrate dehydrogenase. From these experiments it can be concluded that (3R) hydroxybutyrate dehydrogenase from P. lemoignei should be classified as an B or (S) type dehydrogenase.

Hydroxybutyrate Dehydrogenase↗

PubMedDate not supplied

Gamma-hydroxybutyrate versus chlorprothixene/phenobarbital sedation in children undergoing MRI studies.

BACKGROUND: Few clinical studies have assessed gamma-hydroxybutyrate and chlorprothixene/phenobarbital sedation in children. This prospective trial compared the two regimes in children, in particular concerning differences in recovery time. METHODS: 28 pediatric oncology patients undergoing elective MRI studies at a university hospital were randomly assigned to either receive gamma-hydroxybutyrate or chlorprothixene/phenobarbital sedation. Time to induce deep sedation (Ramsay score of 5) and recovery time, the incidence of failure of sedation, the frequency of side effects, the need for therapeutic interventions, and the number of patients receiving additional midazolam were recorded. Analysis of hemodynamic parameters was performed at five defined time points. RESULTS: All 28 MRI studies were successfully completed. Recovery time was significantly shorter with gamma-hydroxybutyrate (p < 0.01). There were more side effects with chlorprothixene/phenobarbital, in particular tachycardia and hyperexcitation. Vomiting was the side effect most often seen in gamma-hydroxybutyrate sedation. Therapeutic interventions were not required in any patient. Additional midazolam was necessary to maintain satisfactory sedation in six children receiving gamma-hydroxybutyrate and four receiving chlorprothixene/phenobarbital. CONCLUSIONS: Due to its significantly shorter recovery time, gamma-hydroxybutyrate is a reasonable sedative drug for children undergoing non-invasive diagnostic procedures, and is superior to chlorprothixene/phenobarbital. In pediatric oncology patients gamma-hydroxybutyrate appears to be associated more often with vomiting. The long recovery time and its great variability make chlorprothixene/phenobarbital a less valuable alternative.

Adolescent↗

PubMed2002

Trends in illicit drug emergencies: the emerging role of gamma-hydroxybutyrate.

BACKGROUND: Previously used as a general anesthetic, gamma-hydroxybutyrate is now used as a recreational drug. Not surprisingly, an increasing number of acute overdose cases requiring emergency medical care have been reported and described, especially in the United States. OBJECTIVES: To determine the number and percentage of gamma-hydroxybutyrate overdoses over a 15-month period and to describe the clinical hallmarks and course of this new drug in overdose. METHODS: All toxicological emergencies, including those caused by illicit drug consumption, were recorded for 15 months in an urban public hospital emergency department. Accurate toxicological history was obtained from the patients and, if gamma-hydroxybutyrate was suspected, confirmation was performed by urine mass spectrometry. The study data were compared with data recorded in the same emergency department in 1989. RESULTS: The total number of toxicological emergencies attended in our emergency department have remained unchanged during the last decade, with a significant decrease in number of opiate overdoses and an increase in the number of cocaine, amphetamine, and gamma-hydroxybutyrate overdoses. During the study period, 104 gamma-hydroxybutyrate overdoses presented to the emergency department (3.1% of all toxicological emergencies), ranking second in illicit drugs requiring emergency consultation. The profile of a patient with gamma-hydroxybutyrate intoxication is well defined: a young individual (23 +/- 5 years), male (64%), emergency department presentation on weekends (90%), with simultaneous ethanol consumption (73%) and ingestion of additional illicit drugs (86%), decrease of consciousness being the main complaint in all cases [16% with Glasgow Coma Scale (GCS) = 3]. Complete recovery without sequelae occurred in all cases. CONCLUSION: Health authorities must be aware of the hazards of recreational gamma-hydroxybutyrate, and physicians must be cognizant of this recent cause of coma among youths presenting to the emergency departments.

Adolescent↗

PubMed1992

gamma-Hydroxybutyric acid in the treatment of alcohol dependence: a double-blind study.

The effect of gamma-hydroxybutyric acid on alcohol consumption and alcohol craving in alcoholics was investigated in a randomized double-blind study versus placebo. Patients were treated as outpatients during a three month period either with gamma-hydroxybutyric acid (50 mg/kg/day, divided into three daily doses) or with placebo. Of the 82 alcoholics that entered the study, 71 completed it, 36 in the gamma-hydroxybutyric acid and 35 in the placebo group. Alcohol consumption was assessed by the subject's self report. At the 3rd month of treatment, 11 patients in the gamma-hydroxybutyric acid group referred to be abstinent and 15 referred controlled drinking; while in the placebo group only two and six patients referred abstinence and controlled drinking, respectively. Serum-gammaglutamyl-transferase activity correlated with the admitted alcohol consumption. Gamma-hydroxybutyric acid treatment decreased alcohol craving during the 3 months of treatment. Transient side effects were noted by six patients on gamma-hydroxybutyric acid and two on placebo. The results suggest that gamma-hydroxybutyric acid may be useful in the treatment of alcohol dependence.

Adult↗

PubMed2003

Gamma-hydroxybutyric acid in the treatment of alcohol withdrawal syndrome in patients admitted to hospital.

Gamma-hydroxybutyric acid is a gamma-aminobutyric acid analogue which can be found in the human brain and is believed to be a neurotransmitter in the central nervous system. In animal experiments as well as in humans gamma-hydroxybutyric acid has been shown to alleviate the symptoms of the alcohol withdrawal syndrome. 299 patients, who were admitted to hospital for reasons primarily unrelated to their alcohol dependence, were treated with gamma-hydroxybutyric acid when symptoms of the alcohol withdrawal syndrome occurred. Gamma-hydroxybutyric acid was usually given at a daily dose of 50 mg/kg in 3 divided doses, the clinical course of the patients was followed for 7 days or until discharge from hospital. Patients were 214 men and 82 women aged 18-87 years. The reasons for admission to hospital were frequently internal diseases, neurological/psychiatric problems, trauma or surgery. At the start of gamma-hydroxybutyric acid treatment, tremor was present in 81% of patients, sweating in 76% and unrest in 92%. Symptoms occurred 1-72 hours after admission. The efficacy of gamma-hydroxybutyric acid to ameliorate or suppress the symptoms of the alcohol withdrawal syndrome was judged to be excellent in 57%, good in 34%, fair in 18%, insufficient in 3% of patients. Drug tolerance was judged to be excellent in 79%, good in 17%, fair in 2% and poor only in 1% of patients. Adverse events were rare and mild. It is concluded that gamma-hydroxybutyric acid is an attractive alternative to tranquilizers in the management of the alcohol withdrawal syndrome in hospital.

Administration, Oral↗

PubMed1985

Plasma levels of glucose, alanine, lactate, and beta-hydroxybutyrate in the unfed spiny dogfish shark (Squalus acanthias) after surgery and following mammalian insulin infusion.

Serial blood samples were collected from the unfed spiny dogfish shark (Squalus acanthias) by use of a cannula chronically implanted in the dorsal aorta. Plasma glucose, alanine, lactate, and beta-hydroxybutyrate levels were estimated by standard enzymatic procedures. The metabolite levels were estimated immediately after the surgery, for an additional 3 to 5 postoperative days before experimental use, and for 7 to 9 days after a single infusion of mammalian insulin (50, 100, and 250 IU/kg body wt) or the control solution. Plasma glucose, alanine, and lactate levels declined for 1 or 2 days after the surgery, but beta-hydroxybutyrate levels were essentially unchanged. Plasma glucose levels remained relatively stable for the remainder of the pretreatment period, and in the control animals during the subsequent treatment period. In contrast, plasma alanine and beta-hydroxybutyrate levels increased during both the pretreatment period and the treatment period in the control animals. Plasma lactate levels increased in the control animals after Day 3 of the treatment period. Insulin infusions resulted in severe, prolonged depressions of plasma glucose and alanine levels. Plasma lactate levels also fell after insulin infusion, but the depressed levels were interrupted by precipitous, large increases, followed by sharp declines, that were evident for one to three sampling periods and whose onset varied between Days 3 and 5 in individual animals. The levels increased again in some animals between Days 6 and 9. Plasma beta-hydroxybutyrate levels were comparatively resistant to insulin. After an early decline, plasma beta-hydroxybutyrate rose to levels that were near the control levels by Days 2 through 4, but fell to near the initial levels by Day 5 and thereafter. The results suggest that the spiny dogfish, a species that consumes reliable and abundant amounts of protein and lipid, but little carbohydrate, and that may feed as seldom as every 2 weeks, uses ketone bodies (beta-hydroxybutyrate and presumably acetoacetate) as primary fuels. Glucose is apparently synthesized by gluconeogenesis, alanine and lactate are probable substrates, and ketone bodies are the likely sources of energy. The evidence supports the hypothesis that glucose is synthesized to maintain muscle glycogen reserves that are used for anaerobic glycolysis when the animal is engaged in predation, escape, or other circumstances that dictate vigorous swimming. If other tissues and organs require glucose as a fuel source, the amounts must be exceptionally small.

3-Hydroxybutyric Acid↗

PubMed1989

Brain 3-hydroxybutyrate, glutamate, and GABA in a rat model of dietary obesity.

Whole brain concentrations of 3-hydroxybutyrate, glutamate and gamma-aminobutyric acid (GABA) have been measured in two strains of rats with differing susceptibility to obesity. S 5B/Pl rats are resistant to developing obesity when eating a high-fat diet, whereas Osborne-Mendel rats readily develop obesity when eating the same diet. We tested the hypotheses that brain 3-hydroxybutyrate, glutamate and GABA differ between S 5B/Pl rats and Osborne-Mendel rats, and that these substrates/neuroregulators are altered when eating a high-fat diet primarily in S 5B/Pl (resistant) rats. Blood and brain 3-hydroxybutyrate concentrations were higher in S 5B/Pl rats than in Osborne-Mendel rats (p less than 0.05) but diet effects were not significant. Brain glutamate concentration, like 3-hydroxybutyrate, was higher in S 5B/Pl rats than in Osborne-Mendel rats (p less than 0.01) and was not affected by adding fat to the diet. Brain GABA differed only slightly between strains but increased after adding fat to the diet (p less than 0.05) in both strains with a greater increase occurring in S 5B/Pl rats. The brains of S 5B/Pl rats are chronically exposed to higher levels of 3-hydroxybutyrate and glutamate than are those of Osborne-Mendel rats. Thus, 3-hydroxybutyrate is a potential signal in the regulation of body weight. Brain GABA increases with fat feeding, especially in S 5B/Pl rats, suggesting that the ability to adjust to an energy dense diet may be through suppression of food intake by elevated brain GABA.

3-Hydroxybutyric Acid↗

PubMed2006

Biosensor for rapid determination of 3-hydroxybutyrate using bi-enzyme system.

A bi-enzyme-based Clark electrode was developed for the determination of 3-hydroxybutyrate. This sensor is based on the specific dehydrogenation by 3-hydroxybutyrate dehydrogenase (HBDH, E.C. 1.1.1.30) in combination with salicylate hydroxylase (SHL E.C. 1.14.13.1). The enzymes were entrapped by a poly(carbamoyl) sulfonate (PCS) hydrogel on a Teflon membrane. The principle of the determination scheme is as follows: the specific detecting enzyme, HBDH, catalyses the specific dehydrogenation of 3-hydroxybutyrate consuming NAD(+). The products, NADH, initiate the irreversible decarboxylation and the hydroxylation of salicylate by SHL in the presence of oxygen. SHL forces the equilibrium of dehydrogenation of 3-hydroxybutyrate by HBDH to the product side by consuming NADH. Dissolved oxygen acts as an essential material for SHL during its enzymatic reactions. This results in a detectable signal due to the SHL-enzymatic consumptions of dissolved oxygen in the measurement of 3-hydroxybutyrate. Interferences from different amino acids and electroactive substances were found to be minimal due to the specificity of HBDH and the application of a Teflon membrane. The sensor has a fast response (2s) and short recovery time (2 min) with a linear range between 8 and 800 microM 3-hydroxybutyrate and a detection limit of 3.9 microM. A good agreement (R(2)=0.9925) with theoretical calculation was obtained in spiked serum sample measurements.

3-Hydroxybutyric Acid↗

PubMed1986

In vivo effect of the D-(-) isomer or natural form of 3-hydroxybutyrate on initial release of lactate dehydrogenase from the acutely ischaemic myocardium.

D-(-)-3-hydroxybutyrate, the isomer found in the circulation and in the urine of diabetic patients, generally is believed to be the physiologically important form of 3-hydroxybutyrate [10]. Little is known concerning the effects of an elevated plasma level of the D-(-) isomer of 3-hydroxybutyrate upon the acutely ischaemic heart. Using anaesthetized intact dogs with a balloon catheter inserted into the proximal part of the left anterior descending coronary artery (LAD), we have recently demonstrated that a 1 mM ketonaemia induced with the arginine salt of D-(-)-3-hydroxybutyric acid reduces the uptake of non-esterified fatty acids (NEFA) in the myocardial area distal to the inflated balloon [4]. The question arises as to whether the concomitant increase in ketone uptake in this area could be detrimental to the acutely ischaemic myocardium. Indeed, a previous study on isolated coronary ligated hearts from normal rats has shown that the rate of release of lactate dehydrogenase (LDH) during the first 90 min of ischaemia can be enhanced by replacing glucose (11 mM) in the perfusion fluid with either albumin-bound palmitate (0.9 mM) or sodium DL-3-hydroxybutyrate (10 mM) as the sole energy substrate [11]. This would suggest that the ketone might be as deleterious as its metabolic precursors for membrane integrity in the acutely ischaemic myocardium. In the present report, we examine the effect of arginine D-(-)-3-hydroxybutyrate on LDH release from ischaemic myocardium in our in vivo preparation. The dogs were treated with lidocaine in order to minimize the frequency and, hence, the adverse metabolic effects of ectopic beats.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Hydroxybutyric Acid↗

PubMed2000

Gamma-hydroxybutyric acid as a signaling molecule in brain.

Gamma-hydroxybutyric acid was synthesized 35 years ago to obtain a GABAergic substance that penetrates the brain freely. Since then, gamma-hydroxybutyric acid has been used in human beings for its sedative and anesthetic properties when administered at high doses, and most of the studies on gamma-hydroxybutyric acid have focused on its pharmacological effects. However, gamma-hydroxybutyric acid is also an endogenous substance, which is synthesized and released in the brain by specific neuronal pathways, implicated in the control of the GABAergic, dopaminergic, and opioid systems. This control is mediated by specific gamma-hydroxybutyric acid receptors with a unique distribution in brain and a specific ontogenesis and pharmacology. Stimulation of these receptors induces specific cellular responses. Taken together, these results suggest that gamma-hydroxybutyric acid possesses most of the properties required of a neurotransmitter/neuromodulator in the brain.

Animals↗

PubMed1970

Ketone body and fatty acid metabolism in sheep tissues. 3-Hydroxybutyrate dehydrogenase, a cytoplasmic enzyme in sheep liver and kidney.

1. 3-Hydroxybutyrate dehydrogenase (EC 1.1.1.30) activities in sheep kidney cortex, rumen epithelium, skeletal muscle, brain, heart and liver were 177, 41, 38, 33, 27 and 17mumol/h per g of tissue respectively, and in rat liver and kidney cortex the values were 1150 and 170 respectively. 2. In sheep liver and kidney cortex the 3-hydroxybutyrate dehydrogenase was located predominantly in the cytosol fractions. In contrast, the enzyme was found in the mitochondria in rat liver and kidney cortex. 3. Laurate, myristate, palmitate and stearate were not oxidized by sheep liver mitochondria, whereas the l-carnitine esters were oxidized at appreciable rates. The free acids were readily oxidized by rat liver mitochondria. 4. During oxidation of palmitoyl-l-carnitine by sheep liver mitochondria, acetoacetate production accounted for 63% of the oxygen uptake. No 3-hydroxybutyrate was formed, even after 10min anaerobic incubation, except when sheep liver cytosol was added. With rat liver mitochondria, half of the preformed acetoacetate was converted into 3-hydroxybutyrate after anaerobic incubation. 5. Measurement of ketone bodies by using specific enzymic methods (Williamson, Mellanby & Krebs, 1962) showed that blood of normal sheep and cattle has a high [3-hydroxybutyrate]/[acetoacetate] ratio, in contrast with that of non-ruminants (rats and pigeons). This ratio in the blood of lambs was similar to that of non-ruminants. The ratio in sheep blood decreased on starvation and rose again on re-feeding. 6. The physiological implications of the low activity of 3-hydroxybutyrate dehydrogenase in sheep liver and the fact that it is found in the cytoplasm in sheep liver and kidney cortex are discussed.

Acetoacetates↗

PubMed1973

D-3-hydroxybutyrate dehydrogenase from Rhodopseudomonas spheroides. Kinetics of radioisotope redistribution at chemical equilibrium catalysed by the enzyme in solutions.

1. The reversible NAD(+)-linked oxidation of d-3-hydroxybutyrate to acetoacetate in 0.1m-sodium pyrophosphate buffer, pH8.5, at 25.0 degrees C, catalysed by d-3-hydroxybutyrate dehydrogenase (d-3-hydroxybutyrate-NAD(+) oxidoreductase, EC 1.1.1.30), was studied kinetically at chemical equilibrium by monitoring radioisotope redistribution with sodium dl-hydroxy[3-(14)C]butyrate and [4-(3)H]NAD(+)(labelled in the nicotinamide ring). 2. When all substrates are maintained at concentrations approaching saturation (approx. 3-50 times the K(m) values) the first-order rate constant for the enzyme-catalysed interconversion of NAD(+) and NADH is much smaller than that for the enzyme-catalysed interconversion of d-3-hydroxybutyrate and acetoacetate. 3. The rate of interconversion of NAD(+) and NADH increases initially with increasing concentrations of d-3-hydroxybutyrate and acetoacetate (ratio of concentrations maintained constant), passes through a maximum and approaches closely to zero at saturating concentrations of the latter substrates. 4. The rates of interconversion of NAD(+) and NADH and of d-3-hydroxybutyrate and acetoacetate increase with increasing concentration of NAD(+) (up to 66 times its K(m) value) and NADH (up to 180 times its K(m) value) (ratio of the concentrations of the nicotinamide nucleotides maintained constant). 5. These findings support the description of this catalysis as an ordered Bi Bi mechanism with no detectable alternative pathway, in which the interconversion of the central ternary complexes is not rate-limiting, and provide no evidence for the formation of dead-end complexes. 6. The solubility of 2,4-dinitrophenylhydrazine in HCl exhibits an acidity optimum, the maximum solubility at 25.0 degrees C (3.8mg/ml, 19mm) occurring at 2.29m-HCl; in solutions of this acidity acetone 2,4-dinitrophenylhydrazone is relatively insoluble (0.098mg/ml, 0.413mm).

Acetoacetates↗

PubMed1983

The storage stability of 3-hydroxybutyrate in serum, plasma, and whole blood.

The storage stability of 3-hydroxybutyrate in whole blood, serum, and plasma was evaluated. The levels of 3-hydroxybutyrate were measured using an enzymatic rate reaction of the specific 3-hydroxybutyrate dehydrogenase with the NAD-NADH coupled reaction. 3-Hydroxybutyrate was found to be a stable analyte in whole blood, plasma, and serum. The long-term stability of beta-hydroxybutyrate allows ample time for separation of blood components and offers storage of samples to meet quality control needs as well as the possibility of mailing specimens. Further studies indicate that NaF plasma, heparin plasma, and serum are the preferred specimens, because both EDTA and oxalate showed the most significant interference with the determination of 3-hydroxybutyrate.

3-Hydroxybutyric Acid↗

PubMed1964

THE ACTION OF SODIUM 4-HYDROXYBUTYRATE ON SPINAL REFLEXES.

The actions of sodium 4-hydroxybutyrate, gamma-aminobutyric acid and meprobamate have been studied in unanaesthetized animals, in local anaesthetic tests, on isolated organ preparations, on convulsions induced by picrotoxin and strychnine, and on monosynaptic (patellar) and polysynaptic (plantar) reflexes of the spinal cord. Sodium 4-hydroxybutyrate induced a sleep-like state with three unusual features: the righting reflex was remarkably persistent, respiration was good throughout and recovery was abrupt. gamma-Aminobutyric acid was inactive and meprobamate caused flaccid paralysis with loss of the righting reflex. None of the agents affected the responses of the rat diaphragm either to direct stimulation of the muscle or to indirect stimulation through the phrenic nerve. Only meprobamate reduced the responses of theguinea-pig isolated ileum preparation, showed local anaesthetic action and had an anticonvulsant action. All three compounds were capable, after intravenous or topical application, of blocking plantar reflexes in doses which did not affect the patellar reflex. The spinal animal responded in the same way, to the same dose of sodium 4-hydroxybutyrate, as the decerebrate preparation. Topical application to the motor cortex had no effect on spinal reflexes. We conclude that sodium 4-hydroxybutyrate acts preferentially on the internuncial neurones in the spinal cord but differs from meprobamate in its other actions. The similarity between the actions of sodium 4-hydroxybutyrate and of gamma-aminobutyric acid provides furtherevidence in support of the hypothesis that sodium 4-hydroxybutyrate is involved in the gamma-aminobutyric acid metabolic pathways.

Aminobutyrates↗

PubMed1999

Construction of environmental DNA libraries in Escherichia coli and screening for the presence of genes conferring utilization of 4-hydroxybutyrate.

Environmental DNA libraries from three different soil samples were constructed. The average insert size was 5 to 8 kb and the percentage of plasmids with inserts was approximately 80%. The recombinant Escherichia coli strains (approximately 930,000) were screened for 4-hydroxybutyrate utilization. Thirty-six positive E. coli clones were obtained during the initial screen, and five of them contained a recombinant plasmid (pAH1 to pAH5) which conferred a stable 4-hydroxybutyrate-positive phenotype. These E. coli clones were studied further. All five were able to grow with 4-hydroxybutyrate as sole carbon and energy source and exhibited 4-hydroxybutyrate dehydrogenase activity in crude extracts. Sequencing of pAH5 revealed a gene homologous to the gbd gene of Ralstonia eutropha, which encodes a 4-hydroxybutyrate dehydrogenase. Two other genes (orf1 and orf6) conferring utilization of 4-hydroxybutyrate were identified during subcloning and sequencing of the inserts of pAH1 and pAH3. The deduced orf1 gene product showed similarities to members of the DedA family of proteins. The sequence of the deduced orf6 gene product harbors the fingerprint pattern of enoyl-coenzyme A hydratases/isomerases. The other sequenced inserts of the plasmids recovered from the positive clones revealed no significant similarity to any other gene or gene product whose sequence is available in the National Center for Biotechnology Information databases.

Amino Acid Sequence↗